1. Field of the Invention
The present invention relates to a method for forming a layer including an organic compound, and further, to a method for manufacturing a light emitting device in which the layer including the organic compound functions as a light emitting layer.
2. Description of the Related Art
A light emitting element in which an organic compound is used as a light emitting body and has characteristics such as low profile, lightness in weight, high speed response, and DC drive at a low voltage is expected to be applied to a next-generation flat panel display. In particular, a display device in which light emitting elements are arranged in a matrix is thought to be superior to a conventional liquid crystal display device in that it has a wide viewing angle and excellent visibility.
It is said that a light emission mechanism of a light emitting element is as follows: when a voltage is applied between a pair of electrodes with an EL layer interposed therebetween, electrons injected from a cathode and holes injected from an anode are recombined at emission centers in the EL layer to form molecular excitons, and energy is released when the molecular excitons relax to the ground state, so that the light emitting element emits light. As excited states, a singlet excited state and a triplet excited state are known, and light emission is possible through either of these excited states.
An EL layer included in a light emitting element has at least a light emitting layer. In addition to a light emitting layer, an EL layer can have a stacked-layer structure including a hole injecting layer, a hole transporting layer, an electron transporting layer, an electron injecting layer, and/or the like.
EL materials for forming an EL layer are broadly classified into low-molecular (monomer) materials and high-molecular (polymer) materials. In general, a film of a low-molecular material is often formed by an evaporation method, and a film of a high-molecular material is often formed by an inkjet method, a spin coating method, or the like.
Reference 1 (Japanese Published Patent Application No. 2001-52864) and Reference 2 (Japanese Published Patent Application No. 2001-102170) have disclosed formation of an EL layer by an inkjet method.